220 Original Articles. | April, 
luminous surface or photosphere, we have little or nothing to guide us 
in this inquiry but the telescopic examination of its surface, which 
reveals to us, besides a general texture of a very peculiar kind, the 
existence of dark spots, temporary in their duration, holding no fixed 
position with respect to its poles and equator, and presenting, in other 
respects, no analogy to those appearances on the planets which indicate 
the existence of local peculiarities on their solid globes, or of con- 
ditions in their atmosphere as to clouds and clear sky which obtain 
in our own. These spots, ever since their complete and recognized 
discovery as such by Fabricius, Galileo, and Scheiner, in 1611 (for 
though occasionally seen before the invention of the telescope, they 
had hitherto been taken for Mercury or Venus in inferior conjunction), 
have always been examined with great though desultory interest : and 
it is only since the year 1843, when Schwabe announced his important 
discovery of the periodicity of their occurrence, that the desirableness 
of keeping up an unbroken record, a complete diary, in fact, of the 
appearances presented by the solar disc, supplying by observations in 
different places the lacunz left by cloudy weather in any one, has been 
recognized. 
During the years antecedent to this epoch, however, a vast amount 
of interesting information had been gathered as to their dimensions 
and forms, their penumbree and umbree (or, as they were sometimes 
called, nuclei,) the facule or veins of brighter light which accompany 
and surround them, or which exist detached and remote from spots ; 
their law of distribution over the surface; their generation, duration, 
and extinction; their appearances, disappearances, and reappearances, 
as carried round with the globe of the sun by its rotation on its axis, 
&c : all particulars very necessary to be borne in mind in reference 
to their physical explanation, as well as to what may be called their 
descriptive history, and of which a brief réswmé may not be thought 
irrelevant as introductory to the more especial subject of this notice, 
which is intended to draw attention to the conclusions which may be 
deduced from certain recent observations of their movements in longi- 
tude and latitude in reference to the equator of the sun’s globe. 
But, first, we have a few words to say on the conditions requisite 
for viewing the sun with effect, and for delineating or photographing 
its spots, which will not be thought out of place by many of that 
numerous class of observers who, with telescopes or other apparatus 
competent to do good service, are without much experience in this 
special line of observation. A very convenient mode of viewing them 
is by projecting the image of the sun in a darkened room, on a white 
screen. This, in its rudest form, was the method followed by Kepler, 
who used only a small hole in a shutter, without a lens, and was thus 
enabled to see a spot on November 29, 1606, and another on May 18, 
1607 (0.8.), which he also took for Mercury (then, however, not in 
transit, and not even in inferior conjunction). If a lens be used to 
bring the rays to a focus, the image, of course, is much improved. 
Still more if it be achromatic : and if in place of a single lens a good 
telescope of moderate focal length be used, and the eye-piece drawn 
out somewhat beyond the focus for parallel rays, an image of a high 
